Queen Elizbaeth II and Prince Philip met with King Felipe VI of Spain and his wife Queen Letizia. They posed for a photograph on Horse Guards Parade in central London.

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The two families go way back. Here are some snaps of Elizabeth with Felipe's father, King Juan Carlos, and the last Spanish state visit in 1986.

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The Royal party was surrounded by soldiers in ceremonial gear, and members of the Queen's personal staff.

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Prince Philip and Felipe inspected an honour guard before proceeding to Buckingham Palace.

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Prime Minister Theresa May, pictured with Home Secretary Amber Rudd, attended the ceremony, but had no formal role in it.

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State visits are conducted by the Queen, not the Government. However, by attending the event Theresa May managed to escape the weekly Prime Minister's Questions sessions, which her deputy took over instead.

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After the inspection at Horse Guards, the monarchs rode together in a horse-drawn carriage to Buckingham Palace.

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The Mall, which leads to the palace gates, had been decked out in Spanish and British flags.

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The royal spouses were taken to the palace in a separate carriage, without the gold linings and smaller coats of arms.

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Both parties were accompanied by members of the Queen's personal bodyguard, the Household Cavalry.

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Elizabeth and Felipe walked down a red carpet at the entrance to Buckingham Palace, where the visit continued out of the public gaze.

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They had a lunch with other members of the Royal family, and drank sherry chosen by Britain's poet laureate, Carol Ann Duffy.

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After lunch the Queen changed into a more casual, floral dress, and showed the Spanish couple around her art collection.

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The ceremonies are due to continue, with the Spanish royals remaining in the UK until Friday.

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Here's what's planned for the rest of the visit:

Wednesday

The Spanish royals will take tea with Prince Charles and the Duchess of Cornwall at Clarence House.

Felipe will then address Parliament in the Royal Gallery and afterwards meet with MPs.

Felipe and Letizia will then be the Queen's quests at a State Banquet at Buckingham Palace.

Thursday

Felipe will go to a meeting at the UK-Spain Business Forum with the Queen's brother, Prince Andrew.

Prince Harry will show Felipe and Letizia around Westminster Abbey, where Felipe will lay a wreath at the Grave of the Unknown Warrior.

Felipe and Letizia will meet prominent Spanish expats at the Spanish Ambassador's house.

Then Felipe will meet Theresa May at 10 Downing Street.

The Spanish royals will be guests at a banquet at London's Guildhall, where he and the Lord Mayor of London will give a speech.

Friday

Felipe and Letizia will formally say goodbye to the Queen and Prince Philip at Buckingham Palace.

Prince Andrew will then take them to the Francis Crick Institute, a major biomedical research centre next to St Pancras station in London, where they will meet Spanish scientists.

Felipe and Letizia's last stop is in Oxford, where they will visit the Bodleian library, be given a private viewing of Spanish treasures held in Oxford.

They will then visit Exeter college, where a professorship in Spanish is named after Felipe's great-grandfather, Alfonso XIII, and meet Spanish students and academics.